Optical scanning laser interference direct writing device and direct writing method

Abstract

The application discloses a light scanning type laser interference direct writing device and a direct writing method. The direct writing device comprises an optical scanning head, an optical path system and a carrier table. The optical scanning head is used to provide a scanning light beam which can move in a certain plane range; the optical path system at least comprises a light splitting device and an imaging assembly which are arranged in sequence along the optical path direction of the scanning light beam. The light splitting device is used to diffract and split the scanning light beam to form at least two coherent laser beams. The imaging assembly is used to refocus the laser beams and form interference fringes to perform laser interference direct writing on an exposure object. The carrier table can be controlled to always keep on the image plane of the imaging assembly and can move in the image plane. The light scanning type laser interference direct writing device has the characteristics of high scanning speed and high control precision of the optical scanning head, and can greatly shorten the direct writing time of the dot matrix interference pattern in combination with the light splitting device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser interference direct writing technology, and in particular to a light scanning laser interference direct writing device and a direct writing method. BACKGROUND

[0002] In the printing field, green printing (inkless printing) has the advantages of no pollution and no noise over traditional printing technologies such as relief printing and inkjet printing, and is conducive to the sustainable development of the printing industry. The mainstream technology process of inkless printing includes converting a target pattern into a dot matrix grating hologram, making the dot matrix grating hologram into a metal template, and using the metal plate to print the dot matrix pattern on the surface of the film material by using the stamping technology.

[0003] How to obtain the dot matrix grating hologram template is a technical difficulty in the process. The laser interference direct writing device is a key device for generating a dot matrix grating pattern. The basic principle is to use two coherent lasers with a certain angle, which are converged at the same point by an optical lens to form a focused spot with an interference grating pattern, and the interference grating angle and the spot moving position are controlled by a computer to scan a grating dot matrix pattern on the surface of a photoresist sample, and then a metal template is formed through development, silver spraying and electroforming processes.

[0004] According to the different dot matrix formation methods, the laser interference direct writing device can be roughly divided into the following two categories: one is to fix the spot and move the photoresist substrate by a high-precision two-dimensional displacement platform to scan the dot matrix. The advantage of this method is that the optical path is simple and the device stability is good; but the disadvantage is that the speed is slow, and the direct writing time of a high-precision large-area dot matrix pattern may be measured in days. The other is to use a DLP or other area array spatial light modulator to obtain multiple grating dot matrices in one exposure, and then use a high-precision displacement table to splice the patterns. The characteristic of this method is that the speed is faster than the first method, but the optical path is complex and the stability is poor; especially a large-diameter beam expander is needed for the laser source, which is easy to introduce other problems affecting the quality of the grating.

[0005] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be regarded as an acknowledgment or any form of suggestion that this information forms prior art that is publicly known. SUMMARY

[0006] The purpose of the present application is to provide a light scanning laser interference direct writing device and a direct writing method, which utilizes the characteristics of fast scanning speed and high control precision of the optical scanning head, and combines with the light splitting device, so as to greatly reduce the direct writing time of the dot matrix interference pattern.

[0007] To achieve the above object, the embodiment of the present application provides a light scanning type laser interference direct writing device, which comprises an optical scanning head, an optical path system and a carrier platform.

[0008] In one or more embodiments of the present application, the optical scanning head comprises a light source and a light scanning device, the light source is used to provide a controllable pulsed laser, and the light scanning device is used to shift the pulsed laser in a certain plane range to form a scanning light beam which can move in a certain plane range.

[0009] In one or more embodiments of the present application, the light source comprises a laser.

[0010] In one or more embodiments of the present application, the light scanning device comprises a MEMS micro mirror or a galvanometer.

[0011] In one or more embodiments of the present application, the optical path system further comprises a focusing device, which is arranged on the optical path of the scanning light beam and located upstream of the light splitting device, and the focusing device is used to make the scanning light beam form a light spot with constant speed and straight line movement.

[0012] In one or more embodiments of the present application, the focusing device comprises an F theta mirror.

[0013] In one or more embodiments of the present application, the light scanning type laser interference direct writing device further comprises a controller, which is used to at least control the optical scanning head to emit the scanning light beam, control the imaging assembly to focus and control the movement of the carrier platform.

[0014] In one or more embodiments of the present application, the light scanning type laser interference direct writing device further comprises a rotary displacement platform, the light splitting device is arranged on the rotary displacement platform, the rotary displacement platform is connected to the controller and can be controlled to adjust the rotation angle and rotation time of itself, so as to control the different directions of the light splitting device to form interference fringes in different directions.

[0015] In one or more embodiments of the present application, the light splitting device comprises a phase grating.

[0016] In one or more embodiments of the present application, the imaging assembly comprises a 4f imaging system composed of a first lens and a second lens, and the light splitting device is located on an object plane of the 4f imaging system.

[0017] In one or more embodiments of the present application, the light scanning laser interference direct writing device further comprises a light shielding device, which is arranged on a surface of the first lens or a back focal plane center of the first lens, and does not completely cover the surface of the first lens or the back focal plane of the first lens.

[0018] The present application also provides a light scanning laser interference direct writing method, which uses the light scanning laser interference direct writing device described above, and comprises: an optical scanning head generating a scanning beam capable of forming a target pattern and making the scanning beam enter the optical path system; and a light splitting device in the optical path system rotating to perform laser interference direct writing of the target pattern, wherein different rotation angles of the light splitting device correspond to different colors of the target pattern; and a stage moving to perform pattern splicing to form laser interference direct writing of a complete target pattern.

[0019] In one or more embodiments of the present application, the optical scanning head generating a scanning beam capable of forming the target pattern comprises: generating a plurality of dot matrix position files containing pixel point positions of the target pattern by an algorithm program, and storing the dot matrix position files in a controller, wherein each dot matrix position file comprises a binary signal file; obtaining a driving feedback signal of an optical scanning device in the optical scanning head, and performing an AND operation between the driving feedback signal and a binary signal of the dot matrix position file to generate a modulation signal of a light source; and controlling the light source in the optical scanning head to emit laser pulses according to the modulation signal, so as to form the scanning beam.

[0020] In one or more embodiments of the present application, the generating a plurality of dot matrix position files containing pixel point positions of the target pattern by an algorithm program comprises: performing image segmentation on the target pattern to form a plurality of sub-target patterns; performing image color separation on each sub-target pattern to form a plurality of single-color sub-patterns; and generating a plurality of dot matrix position files by an algorithm program from the plurality of single-color sub-patterns, wherein each single-color sub-pattern corresponds to a dot matrix position file, and each dot matrix position file is a binary signal file containing one or more pixel point positions.

[0021] Compared with the prior art, the light scanning laser interference direct writing device of the present application has a scanning speed of the optical scanning head that is several orders of magnitude faster than the prior art scheme of moving a photoresist substrate by a high-precision two-dimensional displacement platform to scan a dot matrix, and the latter has a direct writing time of days, while the light scanning laser interference direct writing device of the present application can scan multiple frames of patterns per second, greatly reducing the direct writing time; by taking advantage of the fast scanning speed and high control precision of the optical scanning head, combined with the light splitting device, the direct writing time of a dot matrix interference pattern can be greatly reduced.

[0022] The optical scanning laser interference direct writing device of the present application, the light emitted by the optical scanning head corresponds to only one point, and there is no need to expand the laser beam, only the laser beam from the light source can be introduced to the optical scanning device, and the optical system is simpler and more stable. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the optical scanning laser interference direct writing device of an embodiment of the present application;

[0024] Figure 2 is a principle schematic diagram of the optical scanning device in the optical scanning laser interference direct writing device of an embodiment of the present application;

[0025] Figure 3 is a scanning pattern schematic diagram of the optical scanning device in the optical scanning laser interference direct writing device of an embodiment of the present application;

[0026] Figure 4 is a principle diagram of the light splitting device in the optical scanning laser interference direct writing device of an embodiment of the present application;

[0027] Figure 5 is a schematic diagram of the imaging assembly in the optical scanning laser interference direct writing device of an embodiment of the present application;

[0028] Figure 6 is a light shielding area schematic diagram of the light shielding device in the imaging assembly of an embodiment of the present application;

[0029] Figures 7-9 is a flow schematic diagram of the optical scanning laser interference direct writing method of an embodiment of the present application. DETAILED DESCRIPTION

[0030] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0031] Unless otherwise explicitly stated, in the entire specification and claims, the term "comprise" or its variants such as "contain" or "include" and the like will be understood to include the stated element or component, but not to exclude the presence of other elements or components.

[0032] As described in the background, the current laser interference direct writing device has the disadvantages of slow direct writing speed and long pattern lithography period. In view of the above technical problems, the present application proposes an optical scanning laser interference direct writing device and a direct writing method. The direct writing device utilizes the characteristics of fast scanning speed and high control precision of the optical scanning head, and combines the light splitting device, so that the direct writing time of the dot matrix interference pattern can be greatly reduced.

[0033] The optical scanning laser interferometric direct writing apparatus of the present invention includes an optical scanning head, an optical path system, and a stage. The optical scanning head provides a scanning beam that can move within a certain plane range. The optical path system includes at least a beam splitter and an imaging component arranged sequentially along the optical path direction of the scanning beam. The beam splitter diffracts and splits the scanning beam to form at least two coherent laser beams. The imaging component refocuses the laser beam and forms interference fringes for laser interferometric direct writing on the exposed object. The stage can be controlled to always be held on the image plane of the imaging component and can move within the image plane. The optical scanning head includes a light source and an optical scanning device. The light source provides adjustable pulsed laser light, and the optical scanning device deflects the pulsed laser light within a certain plane range to form a scanning beam that can move within a certain plane range.

[0034] In the optical scanning laser interference direct writing device of the present invention, the scanning speed of the optical scanning head is several orders of magnitude faster than the existing scheme that uses a high-precision two-dimensional displacement platform to move the photoresist substrate to scan the dot matrix. The optical scanning laser interference direct writing device of the present invention can scan multiple frames of patterns per second, greatly reducing the direct writing time, and does not require laser beam expansion; it only needs to draw the laser from the light source to the optical scanning device, making the optical system simpler and more stable.

[0035] The specific implementation of the optical scanning laser interferometric direct writing device of the present invention will be described in detail below with reference to a specific embodiment and accompanying drawings.

[0036] like Figure 1 As shown, one embodiment of the present invention provides an optical scanning laser interferometric direct writing device, including a laser 10, an optical scanning device 20, a focusing device 30, a beam splitting device 40, an imaging component 50, a stage 60, and a controller 70. The optical scanning device 20, focusing device 30, beam splitting device 40, imaging component 50, and stage 60 are sequentially arranged on the laser beam path emitted by the laser 10. The stage 60 is located on the image plane of the imaging component 50 and can move within the image plane under the control of the controller 70 to stitch together a large-size dot matrix hologram after the current frame is directly written. The controller 70 connects the above-mentioned devices and components to control their joint operation.

[0037] In this embodiment, the optical scanning device 20 is a MEMS micromirror. The laser 10 can modulate and output controllable laser pulses. The principle of the MEMS micromirror is as follows: Figure 2 The micromirror is a reflective mirror that can rotate around two axes, α and β, and can vibrate two-dimensionally at a specific frequency under the drive signal. The laser 10 projects a beam onto the surface of the MEMS micromirror, causing reflection and thus forming a scanning beam within a certain range, such as... Figure 3In other embodiments, the light scanning device 20 can also be a common galvanometer system, but will result in a larger volume of the optical scanning head formed.

[0038] The focusing device 30 in the present embodiment can be an Fθ lens, which converts the rotational movement of the MEMS micro-mirror into a constant-speed linear movement of the light spot on the focal plane by using the distortion effect of the lens. In a common lens, when the laser beam is incident to the lens at an angle θ, the light spot is formed at a position of f tan θ on the focal plane. When θ is small, the distance x of the light spot to the optical axis is almost proportional to θ, but when θ becomes large, the proportionality will not hold. The Fθ lens uses the distortion effect of the lens to make the exit angle tan-1 θ with respect to the incident angle θ, so that even when θ becomes large, the incident angle and the distance of the light spot on the focal plane to the optical axis remain in a simple proportional relationship. Therefore, the scanning laser beam formed after the Fθ lens does not need to be electrically corrected, and can form a light spot with constant-speed linear movement on the focal plane.

[0039] The light splitting device 40 in the present embodiment can be a phase grating, which produces diffraction and has a light splitting function, as shown in Figure 4 The diffraction efficiency of each order of light splitting depends on the duty ratio p / d and the etching depth h. When the duty ratio is 50% and the etching depth is appropriately selected, the 0th order light can be eliminated, and the diffraction efficiency of other high orders is also very low, mainly retaining the ±1st order light. Compared with other diffraction gratings, the energy utilization rate is higher. The phase grating is assembled on an electrically driven rotary displacement table, which is connected to the controller 70 and can be controlled to adjust the rotation angle and rotation time, so as to control the different directions of the phase grating to form interference fringes in different directions. In other embodiments, the light splitting device 40 can also be other optical devices with a light splitting function.

[0040] The imaging assembly 50 in the present embodiment can be a 4f imaging system composed of a first lens 51 and a second lens 52, as shown in Figure 5 The light splitting device 40 is placed at the object plane of the 4f imaging system, and the coherent laser beams split from the light splitting device 40 are refocused at the image plane of the 4f imaging system and form interference fringes. A silicon wafer or metal sheet coated with photoresist is placed at the image plane, and after the exposure reaches the exposure dose of the photoresist, the interference fringes are photoetched on the exposure object, at which time the interference fringes are equal-sized grating fringes. At the same time, in order to reduce the influence of the 0th order light on the photoetching effect, a light shielding device 53 is also arranged on the upper surface of the first lens 51 to shield light. The size of the light shielding area of the light shielding device 53 can be calculated as follows: Figure 6As shown, the light blocking region should be located in the lens region; the light blocking region boundary should not exceed the "positive first-order light boundary of the leftmost light" and the "negative first-order light boundary of the rightmost light" (negative on the left side of the figure); and the light blocking region should be greater than the main polar light (light dotted line in the figure) range of the scanning light, i.e. block all main light without affecting all positive and negative first-order light. In other embodiments, the 0-order light blocking device 53 can also be placed on the focal plane of the 4f imaging system, such as Figure 5 the center of the focal plane. Because the focal plane of the 4f imaging system, i.e. the back focal plane of the first lens 51, is a Fourier transform of the object plane, the center is the 0-order light, which is a low-frequency light component, so the area to be blocked is smaller than in the present embodiment.

[0041] The imaging assembly 50 also includes a light splitting prism 54 and a CCD camera 55, the light splitting prism 54 leading the image of the scanning point into the CCD camera 55 for focus detection, as shown in Figure 1 .

[0042] The object table 60 is a high-precision displacement table in the present embodiment.

[0043] The controller 70 is connected to the laser 10, the light scanning device 20, the focusing device 30, the light splitting device 40, the imaging assembly 50, and the object table 60. The controller 70 includes a host computer and a lower computer.

[0044] In the present embodiment, on the host computer, a series of binary signal files containing pixel position are generated by an algorithm program for the pattern to be engraved, each color of the pattern corresponding to a file, and stored in the lower computer FPGA. The MEMS micro-mirror driving board drives the micro-mirror to resonate, and the driving board feeds back a pulse signal when the MEMS micro-mirror moves one pixel position for each minimum angle, and sends out a frame synchronization signal when a frame is completed. The synchronization signal of the driving board is introduced into the lower computer FPGA. In the lower computer FPGA, the binary signal of the dot matrix grating pattern and the micro-mirror synchronization signal are ANDed, i.e. the modulation signal of the laser (i.e. a laser pulse is emitted when the scanning reaches the pixel position corresponding to the pattern) is generated. The laser 10 is controlled by the lower computer FPGA to emit a laser pulse, which then enters the subsequent optical system. At the same time, the host computer controls the rotation angle of the electrically driven rotary displacement table, and different grating angles correspond to different colors at the same observation angle, so the electrically driven rotary displacement table is uniformly rotated by a certain angle when engraving different color layers (for example, when 16 colors are displayed, each color is engraved for 180° / 16 = 11.25°). Finally, after completing the direct writing work of the current region, the host computer controls the high-precision displacement table to move the spliced pattern to achieve the production of a large-size dot matrix grating hologram.

[0045] As shown in Figure 7As shown, the present application also provides a light scanning laser interference direct writing method, using the above-mentioned light scanning laser interference direct writing device, comprising: the optical scanning head generates a scanning beam that can form a target pattern and makes the scanning beam enter the optical path system s1; the light splitting device in the optical path system rotates to perform laser interference direct writing s2 of the target pattern, wherein different rotation angles of the light splitting device correspond to different colors of the target pattern, and the light splitting device waits for the end of the lithography of this layer of color pattern after rotating to an angle, and then performs lithography of the next layer of color, and the trigger signal for starting rotation is the above-mentioned frame synchronization signal; the stage moves to splice the patterns to form laser interference direct writing s3 of the complete target pattern.

[0046] As shown in step s1, the optical scanning head generates a scanning beam that can form a target pattern, specifically comprising: generating a plurality of dot matrix position files containing pixel point positions of the target pattern by an algorithm program, and storing them in the controller s11, wherein each dot matrix position file includes a binary signal file; obtaining the driving feedback signal of the light scanning device in the optical scanning head, and performing AND operation with the binary signal of the dot matrix position file to generate a modulation signal of the light source s12; controlling the light source in the optical scanning head to emit a laser pulse according to the modulation signal to form a scanning beam s13. Figure 8 As shown in step s11, generating a plurality of dot matrix position files containing pixel point positions of the target pattern by an algorithm program specifically comprises: image segmentation of the target pattern to form a plurality of sub-target patterns s111; image color separation of each sub-target pattern to form a plurality of single-color sub-patterns s112; generating a plurality of dot matrix position files by an algorithm program from the plurality of single-color sub-patterns s113, wherein each single-color sub-pattern corresponds to a dot matrix position file, and each dot matrix position file is a binary signal file containing one or more pixel point positions.

[0047] Figure 9 Compared with the prior art, the light scanning laser interference direct writing device of the present application has a scanning speed of the optical scanning head that is several orders of magnitude faster than the prior art scheme of moving the photoresist substrate by a high-precision two-dimensional displacement platform to scan the dot matrix, and the latter has a direct writing time of days, while the light scanning laser interference direct writing device of the present application can scan multiple frames of patterns per second, greatly reducing the direct writing time; by taking advantage of the fast scanning speed and high control precision of the optical scanning head, combined with the light splitting device, the direct writing time of the dot matrix interference pattern can be greatly reduced.

[0048] The light scanning laser interference direct writing device of the present application has only one dot corresponding to one beam of light emitted by the optical scanning head, and does not need to perform laser beam expansion, but only needs to draw laser light from the light source to the light scanning device, so that the optical system is simpler and more stable.

[0049] The light scanning laser interference direct writing device of the present application has only one dot corresponding to one beam of light emitted by the optical scanning head, and does not need to perform laser beam expansion, but only needs to draw laser light from the light source to the light scanning device, so that the optical system is simpler and more stable.

[0050] ​The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims appended hereto.

Claims

1. An optical scanning laser interference direct writing apparatus characterized by comprising: The application relates to a laser interference direct writing device, which comprises the following parts: an optical scanning head for providing a scanning light beam which can move in a certain plane range; an optical path system which at least comprises a light splitting device and an imaging assembly arranged in sequence along the optical path direction of the scanning light beam, the light splitting device is arranged on a rotary displacement table, the light splitting device is used for diffracting the scanning light beam to form at least two coherent laser beams, and the imaging assembly is used for refocusing the laser beams and forming interference fringes to perform laser interference direct writing on an exposure object; a carrier table which can be controlled to always keep on the image plane of the imaging assembly and can move in the image plane; wherein the optical scanning head generates a scanning light beam which can form a target pattern and makes the scanning light beam enter the optical path system; the light splitting device in the optical path system rotates to perform laser interference direct writing of the target pattern, different rotating angles of the light splitting device correspond to different colors of the target pattern; and the carrier table moves to perform pattern splicing to form laser interference direct writing of a complete target pattern.

2. The light-scanning laser-interferometric direct-writing apparatus of claim 1, wherein, The optical scanning head comprises a light source for providing controllable pulsed laser and a light scanning device for making the pulsed laser deviate in a certain plane range to form a scanning light beam which can move in a certain plane range.

3. The optical scanning laser interference direct writing apparatus according to claim 1, wherein Further comprising a focusing device arranged on the optical path of the scanning light beam and located upstream of the light splitting device, the focusing device is used for making the scanning light beam form a light spot of uniform linear motion.

4. The optical scanning laser interference direct writing apparatus according to claim 1, wherein Further comprising a controller used for at least controlling the optical scanning head to emit the scanning light beam, controlling the imaging assembly to focus and controlling the movement of the carrier table.

5. The optical scanning laser interference direct writing apparatus according to claim 4, wherein The rotary displacement table is connected with the controller and can be controlled to adjust the rotating angle and rotating time thereof to control the different directions of the light splitting device to form interference fringes in different directions.

6. The optical scanning laser interference lithography apparatus of claim 1, wherein, The imaging assembly comprises a 4f imaging system composed of a first lens and a second lens, and the light splitting device is located on the object plane of the 4f imaging system.

7. The optical scanning laser interference lithography apparatus of claim 6, wherein, Further comprising a light shielding device arranged on the surface of the first lens or the center of the back focal plane of the first lens, and the light shielding device does not completely cover the surface of the first lens or the back focal plane of the first lens.

8. An optical scanning laser interference direct writing method using the optical scanning laser interference direct writing apparatus according to any one of claims 1 to 7, characterized by The optical scanning head generates a scanning light beam which can form a target pattern and makes the scanning light beam enter the optical path system; The light splitting device in the optical path system rotates to perform laser interference direct writing of the target pattern, wherein different rotating angles of the light splitting device correspond to different colors of the target pattern; The carrier table moves to perform pattern splicing to form laser interference direct writing of a complete target pattern. The optical scanning head generates a scanning light beam which can form the target pattern, comprising the following steps:

9. The optical scanning laser interference direct writing method according to claim 8, wherein, generating a target pattern by an algorithm program to obtain a plurality of dot matrix position files containing pixel point positions, and storing the dot matrix position files in a controller, wherein each dot matrix position file comprises a binary signal file; obtaining a driving feedback signal of a light scanning device in the optical scanning head, and performing an AND operation between the driving feedback signal and the binary signal of the dot matrix position file to generate a modulation signal of a light source; ​ A light source in the optical scanning head is controlled to emit laser pulses in accordance with the modulation signal to form a scanning beam.

10. The optical scanning laser interference direct writing method according to claim 9, wherein The target pattern is divided into a plurality of sub-target patterns by image segmentation. Each sub-target pattern is divided into a plurality of monochromatic sub-patterns by image color separation. The plurality of monochromatic sub-patterns are generated into a plurality of dot matrix position files by an algorithm program, wherein each monochromatic sub-pattern corresponds to a dot matrix position file, and each dot matrix position file is a binary signal file containing one or more pixel point positions. ​

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